Facade in Java

class PointCarte {                           // 1. Subsystem

   private double x, y;

   public PointCarte( double xx, double yy ) { x = xx;   y = yy; }

   public void   move( int dx, int dy )      { x += dx;  y += dy; }

   public String toString()                  { return "(" + x + "," + y + ")"; }

   public double getX() { return x; }        public double getY() { return y; } 

}

 

class PointPolar {                           // 1. Subsystem

   private double radius, angle;

   public PointPolar( double r, double a )   { radius = r;  angle = a; }

   public void   rotate( int ang )           { angle += ang % 360; }

   public String toString()         { return "[" + radius + "@" + angle + "]"; }

}

 

class Point {                                // 1. Desired i/f: move(), rotate()

   private PointCarte pc;                    // 2. Design a "wrapper" class

   public Point( double xx, double yy ) { pc = new PointCarte( xx,yy ); }

   public String toString()             { return pc.toString(); }

   public void move( int dx, int dy )   { pc.move( dx,dy ); } // 4. Wrapper maps

   public void rotate( int angle, Point o ) {

      double x = pc.getX() - o.pc.getX(), y = pc.getY() - o.pc.getY();

      PointPolar pp = new PointPolar( Math.sqrt(x*x+y*y),

                                      Math.atan2(y,x)*180/Math.PI );

      pp.rotate( angle );                                     // 4. Wrapper maps

      System.out.println( "   PointPolar is " + pp );

      String str = pp.toString();  int i = str.indexOf( '@' );

      double r = Double.parseDouble( str.substring(1,i) );

      double a = Double.parseDouble( str.substring(i+1,str.length()-1) );

      pc = new PointCarte(r*Math.cos(a*Math.PI/180) + o.pc.getX(),

                          r*Math.sin(a*Math.PI/180) + o.pc.getY() );

}  }

 

class Line {

   private Point o, e;

   public Line( Point ori, Point end )  { o = ori;  e = end; }

   public void   move( int dx, int dy ) { o.move( dx, dy );  e.move( dx, dy ); }

   public void   rotate( int angle )    { e.rotate( angle, o ); }

   public String toString()       { return "origin is " + o + ", end is " + e; }

}

 

class FacadeDemo {

   public static void main( String[] args ) {

      Line line1 = new Line( new Point(2,4), new Point(5,7) );  // 3. Client

      line1.move(-2,-4);                                        //    uses the

      System.out.println( "after move:   " + line1 );           //    Facade

      line1.rotate(45);

      System.out.println( "after rotate: " + line1 );

      Line line2 = new Line( new Point(2,1), new Point(2.866,1.5) );

      line2.rotate(30);

      System.out.println( "30 degrees to 60 degrees: " + line2 );

}  }